symptoms, however, after continuing
for a variable length of time, almost always ultimately disappear.

Under the name of the _Malum Egyptiacum_, Aretaeus in the 2nd century
gives a minute description of a disease which in all its essential
characteristics corresponds to diphtheria. In the 16th, 17th and 18th
centuries epidemics of diphtheria appear to have frequently prevailed
in many parts of Europe, particularly in Holland, Spain, Italy, France,
as well as in England, and were described by physicians belonging to
those countries under various titles; but it is probable that other
diseases of a similar nature were included in their descriptions, and no
accurate account of this affection had been published till M. Bretonneau
of Tours in 1821 laid his celebrated treatise on the subject before the
French Academy of Medicine. By him the term _La Diphtherite_ was first
given to the disease.

Great attention has been paid to diphtheria in recent years, with some
striking results. Its cause and nature have been definitely ascertained,
the conditions which influence its prevalence have been elucidated, and
a specific "cure" has been found. In the last respect it occupies a
unique position at the present time. In the case of several other
zymotic diseases much has been done by way of prevention, little or
nothing for treatment; in the case of diphtheria prevention has failed,
but treatment has been revolutionized by the introduction of antitoxin,
which constitutes the most important contribution to practical medicine
as yet made by bacteriology.

Causation.

The exciting cause of diphtheria is a micro-organism, identified by
Klebs and Loffler in 1883 (see PARASITIC DISEASES). It has been shown by
experiment that the symptoms of diphtheria, including the after-effects,
are produced by a toxin derived from the micro-organisms which lodge in
the air-passages and multiply in a susceptible subject. The natural
history of the organism outside the body is not well understood, but
there is some reason to believe that it lives in a dormant condition in
suitable soils. Recent research does not favour the theory that it is
derived from defective drains or "sewer gas," but these things, like
damp and want of sunlight, probably promote its spread, by lowering the
health of persons exposed to them, and particularly by causing an
unhealthy condition of the throat, rendering it susceptible to the
contagion. Defective drainage, or wan